Greed should be put aside when you are on the market - especially.
Because otherwise, there would probably be only losses, and no good results would ensue due to temptations.
Yep. We should avoid being greedy because it may ruin our plan. When it meets the target, it is better to take profits as quick as possible because the chance may only come once. If we become greedy, we may miss the chance/opportunity. Then, we may only get smaller profits, or even we got a lose. I've experienced this many times, I missed the chance to get thousands dollars because of being greedy. At the end of the day, I don't get anything (even a cent).
I said this before and I will throw more light on the issue of greed on trading. It is importance to note that trading with small capital is a factor that brings in greed, though there are people who are naturally greedy. However, on a normal situation, a trader with large capital will likely exist the market more often than a trader with a small capital.
For example, a Trader with a capital like $10k, will likely close is position faster, with an average profit rates, than a trader with a little capital like $500.
A trader that trade with small capital will delay to close his position or take profit with a average profit and may become very greedy, because he may desired an improve profit rate to close his position when the market increases further, but will losses if the market dumps.